Manufacture of artificial asphalt, stone, &amp;c.



UNITED STATES Patented December 29, 1903.

PATENT OFFICE.

MANUFACTURE OF ARTIFICIAL ASPHALT, STONE, 8cc-.

SPECIFICATION forming part of Letters Patent No. 748,019, dated December29, 1903. Application filed May 8, 1903. Serial No. 156,282. (Nospecimens.)

.To all whom it may concern:

Be it known that I, CARL RUBITSGHUNG, a subject of the German Emperor,residing at Frankfort-on-the-Main, Germany, have invented certain newand useful Improvements in the Manufacture of Artificial Asphalt, Stone,or the Like, of which the following is a specification.

This invention relates to a process for the manufacture from dividedstony material or the like of a dry granular transportable materialsuitable for use in the manner of stamped asphalt for paving roadways orfor making artificial stone or moldings of artificial stone. p

The essential feature of the invention is the fact that the desired hotmaterial is not molded and formed into bricks while still hot, but, onthe contrary, prevented from coagulating and converted into a drytransportable granular mass, which can be subsequently reheated andpressed into artificial stone blocks or other bodies or used forroad-paving in the manner of stamped asphalt.

The thin li uid tarwhich is rendered free from water an only slightlythickened by moderate heat, in no case above 200, is mixed for a shorttime with divided stony material, more particularly gravel, the mixturebeing thoroughly stirred and the proportion, by weight, of the stonymaterial being several (times five to ten times) that of the tar. Themixing is only continued until the mixture is complete,when it will nolonger stain on being touched and will feel like drymortar. This caneither be performed by bringing the mixed material while stirring it tothe temperature referred to and maintaining the latter fora shor t timeor the stone and the tar can both be separately heated and thensubjected for a'short time to the necessary stirring or working uptogether until the mixture has reached the condition described. In thiscondition the material possesses exceptionally great binding power, sothat in cooling it becomes converted into hard solid masses. The latterare produced without considerable external pressure-in fact, solely bythe pressure of the weight of the mass itself if the material is allowedto cool in this condition. It was therefore hitherto impossible to allowthe material to cool for subsequent use for road-paving or for molding,especially in a different locality.

It has hitherto always been subjected to furdesired shape at the spotwhere it is to be used. In view of the uneven cooling and theabove-mentioned property of the material the use thereof in a hotcondition is inconvenient.

The object of the new process is to obtain aportable product capable ofcohesion which can be used for the desired purpose of manufacture at anytime and at any distance from the place where it was made. In thisprocess the separate heating of the two materials is used, since by thismeans both are previously rendered anhydrous and their action on eachother duringthe mixing can be considerably shortened.

During the mixing the stone absorbs the tar into its pores with avidity,more particularly if the stone is hotter than the tar, and it alsobecomes coated with a close and fine skin of tar, which subsequentlycements the particles together. As soon as the mixture is practicallydry to the touch the mixing operation is complete. Instead of placingthis hot material in molds or pressing it it is powerfully cooled whileleaving the mixing apparatus in a loose condition and is prevented fromcaking together. It can, for instance, be caused to fall from aconsiderable height through cold air onto a wide-meshed shaking sieve orseveral such sieves or the like, so that it is collected in a moreorless finely divided granular form, possibly containing small lumps.Large lumps which remain on the sieves can subsequently be mechanicallybroken up and mixed with the mass.

The larger the proportion of stone material to tar the more surely isthe formation of lumps prevented. This fact leads to a modification ofthe process, which consists in mixing with the stony material a quantityof thin liquid tar, which is insufficient for the necessary binding. Inthis case a small percentage of a pulverized binding agent dry when itis cold-for instance, pitch-is subsequently added to the mass. Pitch forthis purpose is preferably prepared by distilling tar to a less extentthan is usually done where pitch is the residue from completedistillation. The distillation should only be continued until a sampleof the original tar has no longer the staining properties of tar andcongeals on cooling. This pitch can be ground to a powder and issuitable for the purpose described. When subsequently reheated, thepulverized pitch in the mixture melts and assists the binding action ofthe tar, so that the cohesion becomes sufficient. heating, the productcan be molded into arti'cles-such as paving-stones, slabs, pipes, andthe like0r used in the manner of stamped asphalt for paving roadways.

It is obvious that with the process described the addition of sawdust isalso admissible and may be of advantage for the purpose in view.

After re sequently adding a pulverized dry binding agent substantiallyas described;

In witness whereof I have signed this specification in the presence oftwo witnesses.

CARL RUBITSCHUNG.

Witnesses:

J EAN GRUND, CARL GRUND.

